The purpose of this project is to evaluate the overall and age-specific incidence rates of various chronic pain syndromes, and to investigate the relationship between occurrences of these pain conditions with various epidemiological factors. The incidence rates of disabling and/or severe headache were evaluated with data obtained from a Mid-West non-clinical population survey. The use of incidence and prevalence rates in the estimation of length of illness due to headache has been examined. A report of the results of this study has been prepared.